Can Marine Economic Development Demonstration Zones (MEDDZs) achieve a sustainable balance between economic development and ecological protection: Evidence from Chinese coastal cities

Resolving the dilemma of marine sustainable development requires seeking a balance between economic growth and ecological protection. This study treats the policy of Marine Economy Development Demonstration Zones (MEDDZs) as a quasi-natural experiment, relying on data from 47 coastal cities in China from 2004 to 2022. A difference-in-differences (DID) model is constructed to evaluate whether the policy of MEDDZs can achieve a balance between coastal economic development and ecological protection. The findings indicate that the policy of MEDDZs not only drives economic growth in coastal areas but also improves ecological quality, this result holds after considering the validity, endogeneity and robustness of the model. Heterogeneity analysis reveals that, compared to the eastern and southern marine economic circle, there is still considerable room for optimization of the policy effects in the northern marine economic circle. Moreover, synergies with environmental regulation policies can amplify the balancing effects. Mechanism analysis shows that green innovation is the core path for balancing economic development and ecological protection in the MEDDZs, and the green collaborative innovation mechanism performs better than the green independent research and development mechanism. Cost analysis suggests that, compared to implementing ecological protection, promoting economic transformation is the preferred solution for the MEDDZs to balance coastal economic development and ecological protection. Spatial analysis shows that, although the spatial spillover effects of the MEDDZs lead to Pareto improvements, they align with the requirements of regional coordinated development. This study concludes that, in the future, the MEDDZs must balance economic development and ecological protection to serve the fundamental goal of green and coordinated development of the marine economy.